Improvement in dovetailing-chisel



@wat @time NEWTON H. ROBINSON, OF OWASSO, MICHIGAN;

Letters Patent No. 103,659, dated May 3l, 1870.

IMPROVEMENT IN DOIVETAILING-CHISEL- v The Schedule referred to in these Letters Patent and making part of the name.

To all whom. it may concern Be it known that I, NEWTON H. ROBINSON, of Owasso, in the county of Shia'wassee and State of Michigan, have invented certain new and useful Improvements in Dovetailing-Tools; and do hereby declare thatthe following is a full, clear, and exact description ot'vthe same, reference being had to the accom- 'panying drawing making a part of this specification, in which y I` Figurel is a front elevation of my device.I

Figure 2 is a rear elevation of the same.

Figure 3 is aplan view of the cutting-edge of the tool, and

Figure 4 shows the style of joint formed.

Letters of like name and kind refer to like parts in each ofthe figures.

My invention has for its object the production ot' doretail joints for drawers, boxes, Ste., withoutlaying out the work, 4as is usually done; and to this end 1t consists in the peculiar shape of the chisel used for cutting the tenons, as is hereinafter setforth.

The 'oint produced by my device has a round tenon fitting into a corresponding mortise, said mortise being formed by means of an auger or bit, while the tenon is usually cut by means of an ordinary hand chisel, although a tool especially designed for this purpose, and cutting one-half each of two tenons, and the intermediate space .between the same, has been employed.

Both of the above-named methods of forming the tenons are, however, open to serious objections the Erst, because of its Want of accuracy and the length of time required, and the last method, by reason of the diiculty expeiienced .in completing a tenon that has been cut upon one side, the tendency of the same being to spring away from the chisel, and thus render said tenon one-sided and inaccurate.

These objections are removed byl my device, which, as shown in the drawing,cousists ot al chisel'havmg a straight face, A, for cutting the shoulders, and of a circular portion, B, for cutting the tenons,'said face being slotted or divided vertically at its points of intei-section with said circular portion, so as to lea-ve a space for the neck of the tenon. y

As thus formed, the chisel is placed wit-hin an ordinary mortising machine, and operated in the usual manner, each downward out making one complete tenon, withoutother laying out of the work than the striking' of a line for the shoulders, and indicating by a mark the relative positions of the tenons, and even such slight guide-marks may be dispensed with by the use of suitable gauges attached to the bed ot the mortising-machine.

Upon completion of the tenons, it only remains to form corresponding mortises in the opposite part of the joint by means of au ordinary anger or bit. lt will be seen that by this method of forming a. joint, boxes, drawers, &c., may be 'secured together with great rapidity, and that, when completed, said articles will. possess all tbe'strength and oii'er all the resistance to lateral' pressure that would be possible if constructed with the angular dove-tail.

Having thus set forth tlienatur'e and merits of my invention,

WhatI claim as new, and desire to secure by Letters Patent, is-

The hereinbefore described dovetailing-tool, provided with the straight and circular cutting-faces A and B, respectively, as is shown and set forth.

N. H. ROBINSON. Witnesses GEO. W. LORING, J. L. QUAOKENBUSH. 

